I agree it might be tricky.... but I don't think any other real winter tires has any mileage warranty whatsoever. I tell you I used mine for 5 years and over 40k miles and I was down to about 5/32 and that last winter they were noticeably worse than the first 4 but still better than any all seasons. I sold my 2006 in February and ended up getting a new set for my 2019. I would have bought a new set regardless for the following winter. You can't let winter tires get down a low as you would on a summer set that is for sure. Many winter tires actually only have winter compound the first few mm and then wear down to more of an all season type rubber once you get past 5/32 anyway.I pulled them up on Tire Rack and they look like good tires. However, I haven't read a tread life warranty like this before. And they also recommend replacing them when tread reaches 5/32 but I really wonder if they will prorate the tires with that much tread life left on the tires if someone takes them up on the recommendation. I know Discount will not prorate unless the tread is 4/32 or less.
"6 Years / 40,000 Miles (when worn to 2/32" depth) Half mileage for rear if different size than front Must be used during winter months only 9/1 to 4/30"
It goes without saying to get them off the car before you start getting hotter weather.